/Engine/Plugins/Runtime/MeshModelingToolset/Source/MeshModelingTools/Public/EditMeshPolygonsTool.h
Insert a chain of edges across quads (faces with four edges) in the mesh. Due to ambiguity, edges will not be inserted on non-quad faces.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(CallInEditor, Category=ShapeEdits, Meta=(DisplayName="InsertEdgeLoop", DisplayPriority=13)) void InsertEdgeLoop()